Wind energy turbine and wind farm consisting of a plurality of wind energy turbines

ABSTRACT

A wind power facility having a plurality of wind power installations, the wind power installations connected to a current voltage network into which the electrical current generated is fed or delivered that, independent of the currently prevailing amount of wind and the active power that is thus available from the wind power installation, a constant apparent power is always delivered into the network. A device for regulating the power to be delivered to a current voltage network is provided so that the regulation is so adjusted to have a constant apparent power always fed to the network.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention pertains to a wind power installation and,more particularly, to a wind park comprising a plurality of wind powerinstallations configured to generate constant apparent power.

[0003] 2. Description of the Related Art

[0004] Wind power installations, such as a wind park consisting of windpower generators, are usually connected to a current voltage networkinto which the electrical current generated is fed or delivered.

[0005] The particularity of the current feed in the case of wind powerinstallations is that the greatly fluctuating wind conditions mean thatthe power of the wind that is fed in also correspondingly fluctuates.This differs greatly in relation to other energy generators, such asatomic power stations, water power stations, coal-fired or naturalgas-fired power stations, in which admittedly fluctuations can possiblyalso be found over prolonged periods of time but which do not involvepower fluctuations for relatively short periods of time. Thereforeatomic power stations, water power stations, natural gas-fired powerstations and so forth are rather used to furnish the basic load of anetwork while it is only in areas with continual wind that wind powerinstallations are in a position also to provide a basic current load.

[0006] Therefore, wherever wind power installations that provide inparticular a greatly fluctuating feed of power are connected to thenetwork, the electricity supply utility (ESU) also often has toimplement a stabilising or supporting measure for the network as thereis a wish on the part of the ESU that there are no current and voltagefluctuations in the network.

SUMMARY OF THE INVENTION

[0007] The disclosed embodiment of the invention provides that,independent of the currently prevailing amount of wind and the activepower which is thus available from the wind power installation, a windpower installation or a wind park comprising a plurality of wind powerinstallations always delivers a constant apparent power into thenetwork.

[0008] That apparent power is calculated in accordance with thefollowing formula:

S={square root}{square root over (P²+Q²)}

[0009] wherein S is the apparent power, P is the active power, and Q isthe reactive power. Accordingly, if the available active power risesbecause of a corresponding amount of wind, the proportion of reactivepower is also correspondingly reduced. That relationship can be seen ingreater detail in accompanying FIGS. 1 and 2.

[0010] The advantage of the invention lies in a stabilizing orsupporting action on the current supply network. If little active poweris available, for example as a consequence of the wind being low, thequality of the network can be improved by the provision of reactivepower. That in turn affords reduced voltage fluctuations which moreovercan certainly mean that the delivery of electrical energy into thenetwork has to be reduced if the voltage in the network reaches an upperlimit value. The respective proportion of reactive power can be soadjusted that it is capacitive or inductive.

[0011] If there is sufficient active power, it is delivered to thenetwork and supports the network in the event of a fluctuating powerdemand. The remaining proportion of reactive power can in turn bedelivered in a known manner as inductive or capacitive reactive power.

[0012] Flexible adjustment of the power gradient (dP/dt) permitsadaptation to the reception capability of the network in relation torapid changes in power. Even in a network with dominant wind power, thedescribed apparent power management can already be taken into account inthe planning phase, in particular in relation to necessary networkreinforcement measures in order to implement cost-reducing effects.

[0013] In accordance with one embodiment of the invention, a wind powersystem for delivering power to a network is provided. The systemincludes a plurality of wind power installations having a device forregulating the power to be delivered to the network, the regulationadjusted so that a constant apparent power is always fed to the network.Ideally, the apparent power is calculated in accordance with thefollowing formula:

S={square root}{square root over (P²+Q²)}

[0014] where S is the magnitude of the apparent power, P is themagnitude of the active power, and Q is the magnitude of the reactivepower.

[0015] In accordance with another aspect of the foregoing embodiment,the device for regulating the power comprises a rectifier coupled to thewind power installations, a frequency converter coupled to the rectifierand controlled by a microprocessor coupled thereto.

[0016] In accordance with another embodiment of the invention, a windpark for delivering electric power to a network is provided thatincludes at least one wind power generator configured to generateelectric power in response to wind; a reactive power supply to supplyreactive power; and a regulating device coupled to the at least one windpower generator and to the reactive power supply and configured tosupply constant apparent power to the network.

[0017] In accordance with another aspect of the foregoing embodiment,the regulating device includes a rectifier coupled to the at least onewind power generator, a frequency converter coupled to an output of therectifier, and a microprocessor coupled to an output of the frequencyconverter and having an output coupled to a control input of thefrequency converter to regulate reactive power in reciprocalrelationship with the active power.

[0018] In accordance with another aspect of the foregoing embodiment,the regulating device is configured to combine active power and reactivepower to increase total power output to the network in response tonetwork demand for increased total power.

[0019] In accordance with yet a further aspect of the foregoingembodiment, the reactive power supply comprises one of either acapacitive power supply and an inductive power supply.

[0020] In accordance with another embodiment of the invention, a methodof supplying constant apparent power to a network coupled to a windpower installation having at least one wind-powered generator isprovided. The method includes configuring the at least one wind-poweredgenerator to generate electric power in response to wind; rectifying theelectric power into dc voltage; converting the dc voltage into acvoltage; supplying reactive power; and regulating the active power andreactive power to output a constant apparent power to the network.

[0021] In accordance with an aspect of the foregoing embodiment, thereactive power is regulated in reciprocal relationship with the activepower to achieve the constant apparent power. Ideally, the active powerand the reactive power are regulated in accordance with the followingformula:

S={square root}{square root over (P²+Q²)}

[0022] where S is the magnitude of the apparent power, P is themagnitude of the active power, and Q is the magnitude of the reactivepower.

[0023] In accordance with another aspect of the present invention, adevice for regulating voltage delivered to a network from a wind powerinstallation is provided, the device including a rectifier coupled tothe wind power installation, a frequency converter coupled to therectifier, and a microprocessor coupled to the output of the frequencyconverter and having an output coupled to a control input of thefrequency converter to regulate generated active power and reactivepower from a reactive power supply to output a constant apparent powerto the network.

[0024] It is possible with the embodiment of the present invention thatnot only can the wind acting on a wind power installation be used in theoptimum manner and converted into electrical energy, but in that respectnetworks are also not only operated in a fault-free manner they are alsosupported in terms of their operational efficiency. Therefore, overallincreases in the quality standard of the current fed into the network orthe entire wind power installation, which also actively contributes tothe network quality, is realized. This is made possible by the windpower installation apparent power regulation in accordance with theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The invention is described in greater detail hereinafter by meansof an embodiment with reference to the drawings in which:

[0026]FIG. 1 shows a reactive power/active power time diagram of acontrol of a wind power installation, and

[0027]FIG. 2 is a view of a block circuit diagram of a regulating deviceused in a wind power installation.

DETAILED DESCRIPTION OF THE INVENTION

[0028]FIG. 1 shows a reactive power/active power time diagram of aregulation in accordance with a wind power installation according to theinvention. Therein P denotes the active power and Q the reactive power.

[0029] As can be seen from the diagram, the values in respect of theactive power and also in respect of the reactive power behave inreciprocal relationship with each other. That is to say, with a risingactive power the reactive power falls and vice-versa.

[0030] The sum of the squares of active power and reactive power isconstant in that case.

[0031]FIG. 2 shows a regulating device 10 for implementation of thecontrol according to the invention of a wind power installation. Thecontrol regulating device of the wind power installation firstly has arectifier 16 in which the ac voltage generated in the generator of thewind power installation is rectified (dc voltage intermediate circuit).A frequency converter 18 connected to the rectifier 16 converts the dcvoltage, which is initially the same in the intermediate circuit, intoan ac voltage that is fed into the network 6 in the form of athree-phase ac voltage, by way of the lines L1, L2 and L3. The frequencyconverter 18 is controlled by means of a microcomputer 20, which is partof the overall regulating device 10. For that purpose, themicroprocessor 20 is coupled to the frequency converter 18. The inputparameters for regulation of the voltage and also the phase and thecurrent position, with which the electrical energy available from thewind power installation is fed into the network, are the apparent powerS, the electrical power P of the generator, the reactive power factorcos_ and the power gradient dP/dt. Depending on the respective activepower generated, the reactive power supply is also adjusted, with apredetermined apparent power in accordance with the following formula:

S={square root}{square root over (P²+Q²)}.

[0032] It will be appreciated that it is also possible, if necessary, toalter the operating mode if, for example, it is to be provided that theactive power or reactive power is not to exceed a given value. If, forexample, the ESU of the connected network requires that a given amountof reactive power is always fed into the network, this must be takeninto consideration by suitable regulation. The consequence of the feedin accordance with the invention of a constant apparent power into anenergy supply network or the supply of the feed of a constant apparentpower into the energy supply network is that, with a fluctuating activepower, the reactive power is correspondingly regulated—in reciprocalrelationship with the active power—in such a way that a constantapparent power is achieved.

[0033] In order still to be able to intervene in the network with aconstant apparent power, naturally the active power generated by thewind power installation can also be specifically reduced (for example bypitch control of the rotor blades) in order to feed into the network ahigher (capacitive or also inductive) proportion of reactive power fromthe reactive power supply. Such a measure means that the network canstill be correspondingly positively influenced, even with atheoretically higher available active power.

[0034] In regard to the invention in accordance with the presentapplication it provides not only keeping the voltage constant, but itinfluences the network voltage, in accordance with the wishes of thenetwork operator. Thus, by supplementing the active power proportionwith a reactive power proportion, it is possible to raise the voltagelevel in the network to a desired value. It will be appreciated thatthose effects are inter alia also dependent on the topology of thenetwork. In the case of a high demand for reactive power in theproximity of the wind power installation, however, that reactive powerdoes not have to be transported through the network over long distanceswith corresponding losses. Rather, it can be furnished relatively closeto the consumer by the wind power installation.

[0035] All of the above U.S. patents, U.S. patent applicationpublications, U.S. patent applications, foreign patents, foreign patentapplications and non-patent publications referred to in thisspecification and/or listed in the Application Data Sheet, areincorporated herein by reference, in their entirety.

[0036] From the foregoing it will be appreciated that, although specificembodiments of the invention have been described herein for purposes ofillustration, various modifications may be made without deviating fromthe spirit and scope of the invention. Accordingly, the invention is notlimited except as by the appended claims.

1. A wind power system for delivering power to a network, comprising: a plurality of wind power installations having a device for regulating the power to be delivered to the network, wherein the regulation is so adjusted that a constant apparent power is always fed to the network.
 2. The wind power system of claim 1 wherein the apparent power is calculated in accordance with the following formula: S={square root}{square root over (P²+Q²)} where S is the magnitude of the apparent power, P is the magnitude of the active power, and Q is the magnitude of the reactive power.
 3. The wind power system of claim 2 wherein the device for regulating the power comprises a rectifier coupled to the wind power installations, a frequency converter coupled to the rectifier and controlled by a microprocessor coupled thereto.
 4. A wind park for delivering electric power to a network, comprising: at least one wind power generator configured to generate active power in response to wind; a reactive power supply; and a regulating device coupled to the at least wind power generator and the reactive power supply for supplying constant apparent power to the network.
 5. The wind park of claim 4 wherein the regulating device is configured to supply constant apparent power to the network in accordance with the following formula: S={square root}{square root over (P²+Q²)} where S is the magnitude of the constant apparent power, P is the magnitude of the active power, and Q is the magnitude of reactive power.
 6. The wind park of claim 5 wherein the regulating device comprises a rectifier coupled to the at least one wind power generator, a frequency converter coupled to an output of the rectifier, and a microprocessor coupled to an output of the frequency converter and having an output coupled to a control input of the frequency converter, the microprocessor configured to regulate reactive power in reciprocal relationship with the active power.
 7. The wind park of claim 6 wherein the regulating device is further configured to combine active power and reactive power to increase total power output to the network in response to network demand for increased total power.
 8. The wind park of claim 4 wherein the reactive power supply comprises a capacitive power supply.
 9. The wind park of claim 4 wherein the reactive power supply comprises an inductive power supply.
 10. A method of supplying constant apparent power to a network coupled to a wind power installation having at least one wind-powered generator, the method comprising: configuring the at least one wind-powered generator to generate active power in response to wind; rectifying the active power from the at least one wind-powered generator; converting the rectified power; supplying reactive power; and regulating the active power and the reactive power to output a constant apparent power to the network.
 11. The method of claim 10 wherein the reactive power is regulated in reciprocal relationship with the active power to achieve the constant apparent power.
 12. The method of claim 10 wherein the active power and the reactive power are regulated in accordance with the following formula: S={square root}{square root over (P²+Q²)} where S is the magnitude of the apparent power, P is the magnitude of the active power, and Q is the magnitude of the reactive power.
 13. The method of claim 10 wherein regulating further comprises combining active power and reactive power to increase total power output to the network in response to network demand for increased total power.
 14. A device for regulating power generated from a wind power installation for delivery to a network, the device comprising: a rectifier coupled to the wind power installation to receive power generated in response to wind and to output dc voltage; a frequency converter coupled to the rectifier and configured to receive the dc voltage from the rectifier and to convert the dc voltage into an ac voltage that is output to the network; and a control device coupled to the output of the frequency converter and having an output coupled to a control input of the frequency converter, the control device configured to regulate the frequency converter to output constant apparent power to the network that comprises active power from the dc voltage at the rectifier output with reactive power from a reactive power supply in accordance with the following formula: S={square root}{square root over (P²+Q²)} where S is the magnitude of the apparent power; P is the magnitude of the active power, and Q is the magnitude of the reactive power.
 15. The device of claim 14 wherein the control device comprises a microprocessor configured to regulate voltage supplied to the network as well as current and phase in response to inputs comprising the apparent power S, the active power P, a reactive power factor, and a power gradient dP/dT.
 16. The device of claim 14 wherein the control device is configured to combine active power and reactive power to increase total output voltage to the network in response to network demands for increased total voltage output. 